缺锌对大鼠海马和皮层cAMP/PKA-CREB-BDNF信号转导通路的影响

目的观察缺锌对生长期大鼠海马和皮层cAMP/PKA-CREB-BDNF信号转导通路的影响。方法将Wistar大鼠随机分为足锌组(ZA)、对喂组(PF)和缺锌组(ZD),ZA组和PF组喂饲足锌饲料(30mg/kg),ZD组喂饲缺锌饲料(1.5mg/kg)。饲养一个月后处死动物,取海马和皮层,放免法测定cAMP含量;应用PepTag检测系统测定PKA活性;RT-PCR法检测CREB、BDNFmRNA的表达水平。结果ZD组大鼠海马和皮层中cAMP含量明显高于ZA组,同时皮层cAMP含量还显著高于PF组;与ZA组、PF组比较,ZD组大鼠海马和皮层PKA活性均明显降低,同时CREB、BDNFmRNA表达水平下调。结论大鼠海马和皮层cAMP/PKA-CREB-BDNF通路中多种信号分子的表达异常,可能是缺锌导致认知损伤的重要机制之一。     

缺锌对0～2月龄大鼠免疫功能影响的研究

目的 观察缺锌对0～2月龄大鼠免疫器官及细胞因子分泌的影响,为进一步阐明缺锌影响免疫系统的机制及对婴幼儿期、青少年期合理补锌提供参考依据.方法 将9只Wistar孕鼠产仔后随机分为足锌(ZA)、对喂(PF)和缺锌(ZD)3组,每组3只母鼠.ZA组和PF组喂饲足锌饲料(30mg/kg),ZD组喂饲缺锌饲料(1.Omg/k...     

锌缺乏对生长期雄性大鼠海马泛素C末端水解酶L1表达的影响

[目的]观察缺锌对生长期大鼠海马泛素C末端水解酶L1(UCH-L1)表达的影响。[方法]将SD大鼠随机分为正常组、缺锌配喂组和缺锌组,正常组喂饲常锌饲料(32.5mg/kg),缺锌配喂组喂饲高锌饲料(73.5mg/kg),缺锌组喂饲缺锌饲料(1.2mg/kg)。饲养4周后处死动物,取海马组织,RT-PCR法检测UCH-L1mRNA的表达水平,Westernblot法检测UCH-L1蛋白的表达水平。[结果]与正常组和缺锌配喂组比较,缺锌大鼠海马中UCH-L1mRNA和蛋白的表达水平均显著下调。[结论]缺锌大鼠海马UCH-L1的表达异常,可能是缺锌导致认知损伤的重要机制之一。     

重度缺锌对生长期大鼠海马超微结构及神经递质和抗氧化能力的影响

目的观察重度缺锌对生长期大鼠海马超微结构、神经递质含量及抗氧化能力的影响。方法将Wistar大鼠30只随机分为足锌组(ZA)、对喂组(PF)和缺锌组(ZD),每组10只。ZA组和PF组喂饲足锌饲料(30 mg/kg),ZD组喂饲重度缺锌饲料(1.5 mg/kg)。饲养28d后,观察海马超微结构变化;测定海马和皮层去甲肾上腺素(NE)、5-羟色胺(5-HT)、多巴胺(DA)含量;检测全血、海马及皮层Ach含量;硫代巴比妥法检测血清、海马及皮层丙二醛(MDA)含量及超氧化物歧化酶(SOD)活性及总抗氧化能力(T-AOC)。结果 ZD组大鼠海马CA3区超微结构严重受损;脑组织单胺类神经递质—NE、5-HT和DA含量不同程度升高;全血Ach含量显著升高,皮层Ach含量显著降低,海马Ach含量有下降趋势,但无显著性差异;血清、海马和皮层组织中MDA含量明显升高,而SOD活性、T-AOC水平显著下降。结论重度缺锌可导致大鼠海马CA3区超微结构严重受损,胆碱能及单胺类神经递质含量异常改变,抗氧化防御系统功能降低,这可能是缺锌导致认知损伤的作用机制之一。     

生长期缺锌对大鼠海马Egr家族基因表达影响

目的 研究锌缺乏对生长期大鼠海马Egr家族(Egr1、Egr2、Egr3、Egr4)基因表达的影响,探讨缺锌影响学习记忆的基因转录调节机制.方法 选取刚出生的Sprague-Dawley大鼠3窝,每窝1只母鼠、10只仔鼠,3窝母鼠与仔鼠体重相近,仔鼠雌雄各半;随机分为3组:缺锌组(ZD)、配饲组(PF)、对照组(ZA),实验期60 d;用实时荧光定量PCR检测大鼠海马Egr家族(Egr1、Egr2、Egr3、Egr4)mRNA的表达.结果 大鼠海马Egr1、Egr3、Egr4基因表达在3组大鼠间差异有统计学意义(F值分别为13.631,24.435,21.825,),ZD组(2.44×10~(-3),8.72×10~(-3),1.88×10~(-2))表达量低于PF组(3.13×10~(-3),1.60×10~(-2),2.68×10~(-2))、ZA组(3.96×10~(-3),1.92×10~(-2),3.53×10~(-2)),且PF组低于ZA组;海马Egr2基因表达在各组间差异无统计学意义.结论 缺锌使海马锌指蛋白Egr1、Egr3、Egr4基因表达下调,是影响海马学习记忆的机制之一.     

锌缺乏对生长期大鼠免疫细胞凋亡的影响

目的: 观察饲料锌缺乏对生长期大鼠免疫细胞凋亡的影响,并探讨其分子机制。方法: 通过喂食锌含量不同的饲料,构建生长期缺锌大鼠模型;TUNEL方法原位检测胸腺、脾脏组织淋巴细胞凋亡,半定量RT-PCR方法检测一对凋亡调控基因bcl-2/bax mRNA的表达。结果: 与锌充足组(ZA)和配饲组(PF)相比,缺锌组(ZD)大鼠胸腺、脾脏淋巴细胞凋亡增多,促凋亡基因bax mRNA表达增高,补锌后上述改变可得到恢复。结论: 饲料锌缺乏导致发育中和成熟的淋巴细胞凋亡增多,凋亡调控基因bcl-2/bax表达失衡是重要机制之一。     

锌对应激大鼠海马金属硫蛋白亚型表达的调控作用及机制研究

目的　观察不同锌摄入水平对应激大鼠海马脑区不同金属硫蛋白亚型表达的影响。方法　将Wistar雄性大鼠随机分为 8组 :正常对照组、对喂组、缺锌组和补锌组及其相应的应激组 ,分别给予正常饲料、缺锌饲料和补锌饲料 ,以缺锌动物当日的饲料摄入量作为对喂动物次日的给料量。动物喂饲 1周后开始束缚应激 ,持续 4周。以血红蛋白镉饱和法测定脑组织金属硫蛋白含量 ,分离海马提取总RNA ,以RT PCR检测金属硫蛋白亚型MT -1mRNA和MT -3mRNA。结果　缺锌动物出现血锌含量明显降低 ,脑组织金属硫蛋白含量和海马金属硫蛋白mRNA的表达均出现降低 ,但其表达在缺锌应激组动物仍有明显升高 ;而补锌动物金属硫蛋白的表达有所增加 ,补锌应激组动物的表达增加更加明显。缺锌和缺锌应激组动物的血浆皮质醇、IL -1、IL- 6和NO水平也较其它组显著升高。结论　缺锌可降低动物脑和海马组织中金属硫蛋白的表达 ,但缺锌动物在接受应激刺激后 ,金属硫蛋白的表达仍可明显增加 ;而补锌可增加金属硫蛋白的表达 ,补锌应激使脑组织中金属硫蛋白的表达升高更为显著 ;应激对动物的损伤作用与其锌营养状况有关 ,缺锌可降低机体对应激的抵抗能力。     

缺锌对生长期大鼠肾脏维生素D受体及钙结合蛋白基因表达的影响

【目的】研究锌缺乏对生长期大鼠肾脏维生素D受体(vitamin Dreceptor,VDR)和钙结合蛋白(CaBP)基因表达水平的影响。【方法】新生大鼠随机分为缺锌组(ZD)、配饲组(PF)、对照组(ZA)3窝,每窝10只;21 d断奶后每只分笼饲养,喂养至第60 d处死;取肾脏,用试剂盒抽提组织RNA,用实时荧光定量PCR检测肾脏组织VDR mRNA及CaBP mRNA的表达。【结果】大鼠肾脏VDR基因表达ZD组较PF组下调34.78%,PF组较ZA组下调25.81%,ZD组较ZA组下调51.61%;CaBP基因表达ZD组较PF组下调23.19%,PF组较ZA组下调13.75%,ZD组较ZA组下调33.75%。【结论】锌缺乏通过改变生长期大鼠肾脏VDR的活性而影响VDR mRNA,从而影响靶基因CaBP转录,进而影响肾脏钙重吸收,可能是导致骨生成障碍的机制之一。     

锌对心理应激大鼠不同脑区金属硫蛋白亚型表达的影响

目的:观察不同锌摄入水平对心理应激大鼠不同脑区金属硫蛋白亚型表达的影响。方法:将Wistar大鼠随机分为8组:正常对照组、对喂组、缺锌组和补锌组及其相应的应激组,分别给予正常、缺锌和补锌饲料,以缺锌动物当日的饲料摄入量作为对喂动物次日的给料量。动物喂饲1w后开始束缚应激,持续4w。分别以蛋白印迹法和RT-PCR测定海马、皮质、间脑和嗅球金属硫蛋白含量以及MT-1mRNA和MT-3mRNA的表达;并以ELISA法检测血浆IL-6和IL-1的含量。结果:缺锌动物的血锌含量明显降低,缺锌应激动物不同脑区金属硫蛋白及其亚型mRNA的表达均较缺锌动物明显升高,但其增加幅度低于其它应激组;而补锌应激动物的表达增加幅度最大。缺锌组和各应激组动物的血浆皮质醇、IL-1、IL-6水平出现显著升高。另外,金属硫蛋白在不同脑区的表达水平不同:海马>嗅球>皮质>间脑。结论:不同锌营养状况可影响心理应激动物不同脑区金属硫蛋白的表达,海马脑区表达水平较高可能与海马在应激反应中的重要作用相关联。糖皮质激素及IL-6、IL-1等细胞因子可能对金属硫蛋白的表达发挥了诱导作用。     

锌缺乏及补锌对小鼠胚胎HOX3.5基因表达的影响

为研究锌缺乏及补锌对小鼠胚胎HOX3 5基因表达的影响 ,将昆明种雌性小鼠随机分为缺锌组(ZD)、缺锌后补锌组 (ZR)和常锌对照组 (ZN)。ZD组及ZR组喂饲含锌量为 (3 0± 0 5 )mg kg的缺锌饲料 ,但ZR组小鼠从孕第 7天开始改喂含锌量为 30mg kg的常锌饲料。ZN组小鼠一直食用常锌饲料。经 2 5天喂养后 ,与同系成年雄鼠交配。于妊娠第 12天时处死动物 ,并立刻剖腹取出胎鼠。用地高辛标记的探针 ,采用原位杂交方法检测小鼠胚胎HOXC4(3 5 )基因mRNA在鼠胚冰冻切片上的表达量。结果发现 :ZD、ZR组HOX3 5基因阳性表达的面密度及其平均光密度明显低于ZN组 (P <0 0 5 )。提示 :锌缺乏时可导致HOX3 5基因表达量下降 ,这种调控作用乃发生在胚胎发育的早期 ,从孕早期 (孕 7天 )开始补锌仍无法纠正     

The cognitive impairment induced by zinc deficiency in rats aged 0∼2 months related to BDNF DNA methylation changes in the hippocampus

Objective: This study was carried out to understand the effects of zinc deficiency in rats aged 0～2 months on learning and memory, and the brain-derived neurotrophic factor (BDNF) gene methylation status in the hippocampus.

Methods: The lactating mother rats were randomly divided into three groups (n?=?12): zinc-adequate group (ZA: zinc 30?mg/kg diet), zinc-deprived group (ZD: zinc 1?mg/kg diet), and a pair-fed group (PF: zinc 30?mg/kg diet), in which the rats were pair-fed to those in the ZD group. After weaning (on day 23), offspring were fed the same diets as their mothers. After 37 days, the zinc concentrations in the plasma and hippocampus were measured, and the behavioral function of the offspring rats was measured using the passive avoidance performance test. We then assessed the DNA methylation patterns of the exon IX of BDNF by methylation-specific quantitative real-time PCR and the mRNA expression of BDNF in the hippocampus by RT-PCR.

Results: Compared with the ZA and PF groups, rats in the ZD group had shorter latency period, lower zinc concentrations in the plasma and hippocampus (P?Conclusion: The learning and memory damage in offspring may be a result of the epigenetic changes of the BDNF genes in response to the zinc-deficient diet during 0～2 month period. Furthermore, this work supports the speculative notion that altered DNA methylation of BDNF in the hippocampus is one of the main causes of cognitive impairment by zinc deficiency.     

缺锌对大鼠小肠粘膜维生素D受体及钙结合蛋白基因表达的影响

目的:研究锌缺乏对生长期大鼠小肠粘膜维生素D受体(VDR)和钙结合蛋白(CaBP)基因表达水平的影响。方法:刚断奶的雄性大鼠随机分为缺锌(ZD)、配饲(PF)、对照(ZA)三组,每组10只。喂养15d后处死,取小肠粘膜,用试剂盒抽提组织RNA,用实时荧光定量PCR检测小肠粘膜VDRmRNA及CaBPmRNA的表达。结果:ZD组大鼠小肠粘膜VDR基因表达较PF组下调88.89%,PF组较ZA组VDR基因表达下调50.00%,ZD组较ZA组VDR基因表达下调94.5%。ZD组CaBP基因表达较PF组下调80.16%,PF组较ZA组CaBP基因表达下调39.76%,ZD组较ZA组CaBP基因表达下调88.50%。结论:锌缺乏通过改变VDR的活性而影响VDRmRNA,从而影响靶基因CaBP转录,进而影响钙吸收,导致骨生成障碍。     

Marginal zinc deficiency in rats decreases leptin expression independently of food intake and corticotrophin-releasing hormone in relation to food intake

Zn deficiency reduces food intake and growth rate in rodents. To determine the relationship between Zn deficiency and the regulation of food intake, we evaluated leptin gene expression in epididymal white adipose tissue (eWAT), and hypothalamic corticotropin-releasing hormone (hCRH) and hypothalamic neuropeptide Y (hNPY) of rats Zn-deficient only to show reduced food intake and growth rate but not food intake cycling. Growing male Sprague-Dawley rats (240 g) were randomly assigned to one of four dietary groups: Zn-adequate (ZA; 30 mg/kg diet), Zn-deficient (ZD; 3 mg/kg diet), pair-fed with ZD (PF; 30 mg/kg diet) and Zn-sufficient (ZS; 50 mg/kg diet) (n 8), and were fed for 3 weeks. Food intake and body weight were measured, as were blood mononuclear cells and pancreas Zn levels. eWAT leptin, hCRH and hNPY mRNA levels were determined. Food intake was decreased by about 10 % in ZD and PF rats compared to ZA and ZS rats. Growth and eWAT leptin mRNA levels were unaffected in PF rats but were significantly (P < 0.05) decreased in ZD rats. However, hNPY showed a tendency to increase, and hCRH significantly (P < 0.05) decreased, in both ZD and PF rats. These results suggest that while leptin gene expression may be directly affected by Zn, hNPY and hCRH are likely responding to reduced food intake caused by Zn deficiency.     

Effect of zinc on biochemical parameters and changes in related gene expression assessed by cDNA microarrays in pituitary of growing rats

OBJECTIVE: The present study simultaneously investigated the effects of different zinc (Zn) levels on the growth performance and relative biochemical parameters in growing rats and analyzed the molecular mechanism of zinc influencing food intake. METHODS: Three diets with different Zn levels--Zn adequate (ZA; 35.94 mg/kg, control), Zn deficient (ZD; 3.15 mg/kg), and Zn overdose (ZO; 347.50 mg/kg)--were fed to rats for 6 wk. Dietary Zn was supplemented with ZnSO4. The relation between zinc and food intake was studied by pituitary cDNA microarrays. RESULTS: Compared with ZA group, rats fed the ZD diet showed decreases in body weight (P < 0.01), food intake (P < 0.05), tissue zinc concentrations (P < 0.01), and specific activities of alkaline phosphatase (P < 0.01) and copper/Zn superoxide dismutase (P < 0.05), whereas the ZO diet had positive effects on body weight (P < 0.05), zinc concentrations (P < 0.01), and alkaline phosphatase activity (P < 0.05). The villi of the jejunum became shorter (P < 0.01), shriveled, and flattened. This change in morphology decreased absorption surface area, and there was a substantial decrease (P < 0.01) in villi number per unit area in ZD rats. Metallothionein concentration was increased in livers of rats fed ZD (P < 0.01) and ZO (P < 0.05) diets. Moreover, ZD and ZO influenced normal growth and development of organs. The results from pituitary cDNA arrays indicated that different Zn levels affect gene expression of appetite-related peptides, including neuropeptide-Y, melanin-concentrating hormone, ghrelin, calcitonin gene-related product, and serotonin. CONCLUSION: The present results showed that zinc deficiency has a negative effect on the growth performance and biochemical parameters of rats. The ZO diet increased body weight (P < 0.05) but had no effect (P > 0.05) on food intake, copper/Zn superoxide dismutase activity, and intestinal morphology. The ZD diet decreased rat food intake by regulating appetite-related gene expression in the pituitary gland.     

Plasma apolipoprotein B-48, hepatic apolipoprotein B mRNA editing and apolipoprotein B mRNA editing catalytic subunit-1 mRNA levels are altered in zinc-deficient rats.

Apolipoprotein B (apoB) exists as two major isoforms and serves as an obligatory component of lipid-rich plasma lipoprotein particles. Apolipoprotein B mRNA editing is a zinc-dependent, site-specific cytidine deamination that determines whether the apoB-100 or apoB-48 isoform is synthesized. The objective of this work was to examine whether dietary zinc levels affect apoB mRNA editing in vivo. Adult male Sprague-Dawley rats were randomly assigned to zinc-deficient (ZD, <0.5 mg Zn/kg diet), zinc-adequate (ZA, 30 mg Zn/kg diet) or zinc-replenished (ZDA, ZD rats fed the ZA diet for last 2 d) dietary groups for 18 d. The ratio of plasma apolipoprotein B-48 (apoB-48) to total apoB was significantly lower in zinc-deficient compared with zinc-adequate rats. Primer extension analysis indicated a modest but significant reduction in hepatic apoB mRNA editing in ZD rats compared with that of the ZA group. In ZDA rats, hepatic apoB mRNA editing and the percentage of plasma apoB-48 to total apoB were not different from ZA rats. The mRNA abundance of hepatic apobec-1 (apoB mRNA editing catalytic subunit 1) was significantly lower in ZD and ZDA rats than in ZA rats. In summary, the plasma ratio of apoB-48 to total apoB protein as well as hepatic apoB mRNA editing and hepatic apobec-1 mRNA levels were reduced in rats consuming a zinc-deficient diet. These data suggest that one or more components of apoB metabolism may be influenced by dietary zinc status.     

Reevaluation of zinc deficiency on concanavalin-A-induced rat spleen lymphocyte proliferation

Zinc concentrations of serum, nonlymphoid and lymphoid tissues, and the responsiveness of concanavalin-A (Con-A)-stimulated spleen lymphocytes (SL) and cervical lymph node cells ( CLNC ) from ad libitum-fed zinc-deficient (ZD), pair-fed (PF) and ad libitum-fed zinc-adequate rats (AL) were determined. In vitro effects of serum from ZD, PF and AL rats on responsiveness of Con-A-stimulated SL and CLNC were determined. Weanling male Long-Evans rats were fed ad libitum zinc-deficient (less than 1.0 microgram Zn/g diet) and zinc-adequate (20 micrograms Zn/g diet) diets for 7-42 days. Effects of undernutrition on test parameters were determined on PF rats, which received a restricted zinc-adequate diet (restricted in amount to that consumed by ZD rats). Growth, food intake and zinc concentrations in serum, liver and pancreas were significantly depressed in ZD and PF rats. Zinc per gram of thymus tissue and per number of SL was elevated in ZD and PF rats. Spleen lymphocytes from ZD and PF rats displayed equivalent to significantly increased levels of proliferation following stimulation with Con-A. [3H]Thymidine incorporation by Con-A-stimulated SL and CLNC from ZD, PF and AL rats was not significantly different when cultured in medium containing serum from ZD, PF and AL rats. The present study shows that zinc deficiency causes major changes in total-body and organ growth but minor changes in zinc content and mitogen-induced proliferation of lymphocytes.     

Dietary zinc deficiency decreases glutathione S-transferase expression in the rat olfactory epithelium

Zinc deficiency leads to olfactory and gustatory dysfunction, but little is known about the underlying molecular mechanism of this phenomenon. We examined the effect of dietary zinc deficiency on the rat olfactory epithelium. Immunoreactivities of glutathione S-transferase (GST) mu, neuron-specific enolase (NSE) and proliferating cell nuclear antigen (PCNA), and in situ hybridization of GST mu mRNA in the olfactory epithelia were examined under different dietary zinc intake conditions. Adult male rats were fed a zinc-deficient (ZD) diet (0.5 mg zinc/kg diet), whereas control rats, including pair-fed (PF) and zinc-adequate (ad libitum consumption, AL) groups, were fed a zinc-adequate diet (58 mg zinc/kg diet) for 7 wk. We also examined the effect of zinc replacement (ZR) by subsequently feeding half of the ZD group a zinc-adequate diet for 5 wk after the initial 7-wk deprivation. No significant differences in immunoreactivity for NSE in olfactory epithelial receptor cells or for PCNA in basal cells were noted among groups. Intense GST mu immunoreactivity and hybridization signals were observed in olfactory supporting cells of AL, PF and ZR groups, but very minimal or no such signal was noted in ZD rats. Our findings indicated that zinc deficiency reduces GST mu expression in the supporting cells of rat olfactory epithelia but does not affect receptor cell proliferation or maintenance.